District of



(Nd Model.) I I M. 'WHELESS 8v J. D. DAR-DEN.

TELEPHONE TRANSMITTER.

No. 352,900. Patented Nov. 16,1886.

' UNITED STATES PATENT 1 OFFICE.

MALONE WHELESS AND JAMES D. DARDEN, OF WASHINGTON, DISTRICT'OF COLUMBIA; SAID-WHELESS ASSIGNOR TO SAID DARDEN.

TELEPHONE-TRANSM ITTER.

ESPECIPICATION forming part Letters Patent No. 352,900, dated November 16, 1886.

Application filed March 5, 1886. Serial N0.19-l,159. (No model.)

To all whom it may concern: 1

. Be it knownthat we, MALONE WHELESS and JAMES D. DARDEN, citizens of the United States, residing at Washington, in the District 5 of Columbia, have invented certain new and useful Improvements in Telephone-Transmitters; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. Our invention relates to telephonetransmitters, and has for its object to provide'a transmitter which will admit of more powerful our- 1 5 rents being sent through and overcome the grinding at the receiver,so common in te1e--- phones now in use. This grinding of the carbon is caused by the crystalline formation of the carbon, and acts as a great impedimentto the articulation of the telephone. By our improvements the surface'of the carbon is kept perfectly smooth, maintaining a softness which totally destroys "the metallic ring characteristic in telephony, and gives the advantage of using greater power from the battery without decreasing the utility of the carbon as a resistant, and admits of 7 transmitting messages over long distances without the loss of articulation. The carbon is kept 3o continually in a moist state by means hereinafter more fully described. These objects we attain by the device illustrated in the accompanying drawings, in which Figure 1 represents a vertical sectional view of our transmitter; and Fig. 2 a similar View of the transmitter with an induct-ion coil, cut-out mechanism, and receiver.

Similar letters refer to similar parts throughout the several views. 7

The letterI indicates a sounding-box provided with the usual mouth-piece, t, a dia-" phragm, D, being secured at its top and bottom by means of screws. Attached to the diaphragm is a metallic cup, A, having an open- 5 ing, a, in the under side thereof to receive one end of a tube, '0, filled with a spongy substance, D, the other end of said tube being received in a vessel, 0, which is placed in aconvenient position, and secured by a strap, a, or

other means. In the rear portion of the metallic cup A is placed a small quantity of powdered carbon filtering-paper or other absorbent, and in front of .which is placed asmall carbon button or electrode B. The vessel 0 being filled with water or other liquid, the car- 5 bon button is kept in a moist condition by capillary attraction. The liquid being carried In the transmitter shown in Fig. 1 it will be 7 seen that the, direct battery-current is repreo sented as operating without theinduction-coil, the current passing fromthe battery to the diaphragm, thence to the metallic cup, through the contact-button B to the contact J, thence to the line-wire H at a by means ofthe spring E. A .cut-off, Fig. 2, consisting of aspring,

n, and two metallic contacts, m and m, serves to open the local battery-circuit while the speaker is listening, and gives the inductioncurrent coming into his receiver less resist- 8o ance than it otherwise would have if it passed around the coil through which the battery-circuit is flowing, as is the case with the transmitters in general use.

One pole of the battery R leads to the point P, thencev down to the spring a to the contactpoint, passing through the opposite metallic contact m to the diaphragm D, thence to the metallic cup and carbon to the opposite electrode J,- up the spring E to a, thence to the induction-coil S, and back to the other poleof the battery.

' When the transmitter is not in use,thep0int of contact is always open; but when it is used it is closed by a pressure of the finger upon 5 the button of the contact m, which makes the induction-coil effective. I

We are aware that an electrode of bibulous paper moistened with water fed' by capillary attractlon, and placed between metallic plates,

has heretofore been used. Such a construction differs materially from that which is herein sought to be claimed, in that our-invention consists, essentially, of an absorbent body and a body of hard carbon, the two constituting one of the electrode-contacts.

,Having thus fully described our invention,

what we claim, and desire to secure by Letters Patent, is-

1. A telephone-transmitter, one of whose electrodes consists of a body of moistened absorbent conducting material adjacent to the diaphragm, and a button of hard carbon constitoting the electrode-contact, substantially as specified.

2. A telephone-transmitter, one of whose electrodes consists of abody of moistened powdered carbon adjacent to the diaphragm, and a button of hard carbon constituting the electrode-contact, substantially as specified.

3. A telephone-transmitter having a diaphragm provided with a central socket containing a body of moistened powdered carbon, and a button of hard carbon in front of said diaphragm, a feed-reservoir, and a capillary conveyor between the reservoir and powdered carbon, substantially as described and shown.

In testimony whereof we affix our signatures in presence of two witnesses.

MALONE WHELESS, JAMES D. DARDEN,

Witnesses: J. R. NOTTINGHAM, WILLIAM FITCH. 

